Down Regulation of the Gene Expression by Means of Nucleic Acid-Loaded Virus-Like Particles

ABSTRACT

The present invention relates to compositions of virus-like particles for the introduction of RNA-interference (RNAi-) inducing molecules into eukaryotic cells and methods for the cell type-specific transduction of a plurality of eukaryotic cells with RNAi-inducing molecules. The present invention furthermore relates to methods for a diagnosis, prevention and/or treatment of diseases or disease states associated with an increased expression rate of at least one endogenous gene, and/or with the undesired expression of at least one endogenous gene and/or foreign nucleic acids, in particular viral nucleic acids.

The present invention relates to compositions of virus-like particlesfor the introduction of RNA-interference (RNAi-) inducing molecules intoeukaryotic cells and methods for the cell type-specific transduction ofa plurality of eukaryotic cells with RNAi-inducing molecules. Thepresent invention furthermore relates to methods for a diagnosis,prevention and/or treatment of diseases or disease states associatedwith an increased expression rate of at least one endogenous gene,and/or with the undesired expression of at least one endogenous geneand/or foreign nucleic acids, in particular viral nucleic acids.

Gene-therapeutic methods that are currently known are based on thetransfection of cells with DNA-constructs encoding for a desired geneproduct, mostly a therapeutically effective protein. Methods that areused hereby are usually adapted to in vitro methods. A targeted, i.e.selective, transfection of specific cell types without a prior isolationof the cells from their natural environment can not be realized withmost of the methods of the state of the art, such as, for example,electroporation or liposome transfection.

Methods for a tissue specific DNA-transfer in vivo so far rely on viraltransfer systems. Nevertheless, due to the potential danger ofrecombination with cellular sequences, these bear a safety risk that canhardly be calculated. A repeated in vivo-application of adenoviruses andadeno-associated viruses, the systems that are currently preferred forthe transport of therapeutic genes, is impossible because of their highimmunogenicity in most patients. In addition, due to the complexstructure of the adenovirus and the structure of the adenoviral genomeit is only possible with considerable effort to provide therapeutic DNAat the target site to a sufficient extent and in a suitable form.

Particularly in view of an undesired recombination and the associateddanger to permanently modify the genome, gene-therapeutic methods couldnot be considered for the treatment of transiently occurring diseasestates, such as, for example, acute infections. Non-viral systems, suchas, for example, liposomes and DNA-condensating molecules, indeedavoided these disadvantages, but, in turn, similar to retroviral systemsexhibited much lower transfer efficiencies and target cellspecificities.

Therefore, there is a need to provide clinically applicablegene-therapeutic compositions and methods, in order to avoid theseproblems.

It was the object of the present invention to provide compositions,which, while simultaneously maintaining the integrity of the cellulargenome of a target cell, allow for a cell type specific introduction ofgene-therapeutically effective molecules into eukaryotic cells with highefficiency both in vivo and in vitro. It was a further object of thepresent invention to provide highly efficient methods for the treatmentof pathogenic infections, or for the therapy and/or diagnosis of diseasesymptoms that are associated with a modified gene expression.

According to the present invention, these objects were solved by acomposition comprising a virus like particle (“virus like particle”;VLP) that is composed of several molecules of at least one viral capsidprotein, characterized in that at least one RNA-interference (RNAi-)inducing molecule is included in the VLP. After the transfer into thetarget cell, the RNAi-inducing molecules cause an effectivedown-regulation of the expression of a gene of interest.

RNA-interference (RNAi) is an evolutionary conserved mechanism fordown-regulating the expression of one or several genes (“genesilencing”). A plurality of eukaryotic organisms are able to protectthemselves by means of RNAi against viruses and the expression oftransposon elements. The principle of the down-regulation of geneexpression by means of RNAi is on the one hand based on the sequencespecific degradation of the RNA, in particular mRNA, that is generatedby the transcription of a target gene, based on an interaction of thetranscript with short RNA-molecules comprising, for example, 21-28nucleotides, so-called small interfering RNA-molecules (“smallinterfering RNA”, siRNA). Catalyzed by the RNase III Dicer, the targeteddegradation of an mRNA-molecule first begins with the formation ofdouble-stranded siRNA-molecules from precursor molecules, and asubsequent processing of these molecules, followed by the hybridizationof one strand of the double-stranded siRNA with the mRNA-molecule,forming a double-stranded siRNA-mRNA hybrid molecule. Subsequently, acleavage of the mRNA inside the region as hybridized with the siRNAtakes place. This cleavage or hydrolysis, respectively, first occursendonucleolytically, e.g. catalyzed by the endonuclease argonaute 2 ofthe RISC-complex. Finally, the cleavage products thus generated arehydrolyzed by exonucleases of the RISC-complex. As a cause of thetargeted degradation of mRNA-transcripts, the expression of the targetgene is at least partially suppressed.

On the other hand, the expression of a gene can also be down-regulatedon the translational level. The effector molecules that are responsiblefor this are designated as microRNA (miRNA), which, starting from ahairpin structure (“hairpin”) of a precursor-RNA, are formed throughseveral processing steps involving the endonucleases Drosha, Pasha, andDicer. Because of their partial complementarity with the target-mRNA,miRNAs inhibit the translation thereof.

Studies on cell cultures have shown that also exogenously provided siRNAor miRNA, respectively, can induce an RNA-interference in eukaryoticcells, e.g. mammalian cells, including human cells. Because of the lowtransfer efficiencies, previous methods for introducing RNAi-inducingmolecules into eukaryotic cells do not, or only to a very limitedextent, allow for a use of this mechanism as a therapeutic approach forthe treatment of infections with pathogenic viruses or for the treatmentof diseases that are associated with a modified gene expression.

An RNAi-inducing molecule shall mean those RNA-molecules, wherein atleast one polynucleotide strand has a sequence that is sufficientlycomplementary to a target-RNA, preferably a target-mRNA, in order tocause its processing, i.e. its degradation. In order to be RNAi-inducingit is required that the complementarity between RNAi-inducing moleculeand a region of the target-RNA is sufficient in order to effecthybridization and a subsequent processing. For example, thecomplementarity is at least 80%, preferably at least 90%, and mostpreferred at least 99%, wherein at the 5′- and/or 3′-ends and at theoverhangs of an RNAi-effector molecule also nucleotides can be presentwhich are not complementary to the target-RNA.

In order to induce RNAi, several routes can be followed. Thereby, thedirect transfer of effector molecules, i.e. siRNA-molecules and/ormiRNA-molecules, represents one possibility. An siRNA-molecule shallpreferably mean a double-stranded RNA molecule having a length of 19-30nucleotides, preferably 20-28 nucleotides and particularly preferredhaving a length of 21-23 nucleotides of each of the single strands.siRNA-molecules also mean single-stranded RNA-molecules having a lengthof 19-30 nucleotides, preferably 20-28 nucleotides, and particularlypreferred having a length of von 21-23 nucleotides, wherein the singlestranded RNA-molecule is complementary to a sequence of a target-RNA, inparticular a target-mRNA, to at least 80%, preferably to at least 90%,and in particular to more than 99%, and wherein a binding of the siRNAto the target-RNA effects a sequence-specific degradation. Preferably,the siRNA-molecules have 3′-sided overhangs of 1-3 nucleotides.

MiRNA shall mean single stranded RNAi-inducing molecules having a lengthof 19-30 nucleotides, preferably 20-28 nucleotides, and particularlypreferred having a length of 21-23 nucleotides, which afterhybridization with a target-mRNA can effect both the inhibition of thetranslation, as well as effect the degradation thereof.

Alternatively, it is also possible to provide precursor molecules of theactual effective effector molecules, i.e. precursor molecules of siRNAand/or miRNA, which function as a substrate for thesiRNA/miRNA-biogenesis-apparatus of the target cell. These include, forexample, RNA-precursor molecules, such as double stranded RNA (dsRNA) orshort hairpin RNA-molecules (shRNA), which are processed intosiRNA-molecules or miRNA-molecules, respectively, by the endonucleases,such as Dicer, Drosha, and/or Pasha. For this, for exampledsRNA-molecules or short hairpin RNA-molecules (shRNA) with a length ofmore than 27 nucleotides, preferably more than 30 nucleotides to about100 nucleotides or longer, and most preferably dsRNA-molecules having alength of 30-50 nucleotides can be used.

Besides this, it is also possible to introduce RNAi-inducing moleculesinto the target cells by means of a DNA-based RNAi-approach. For this,DNA-constructs are created, which encode for dsRNA, shRNA, siRNA and/ormiRNA, wherein the encoding elements are under the control of regulatoryelements that allow for an expression of the dsRNA, shRNA, siRNA and/ormiRNA in the target cell. Examples for such control elements arePolymerase II-promoters or Polymerase III-promoters, such as, forexample, U6 or H1.

Surprisingly, using the composition according to the invention it couldnow be found that most diverse kinds of RNAi-inducing molecules could beintroduced into a target cell with an extraordinarily high efficiency ina cell type-specific manner. Thereby, the RNAi-inducing molecules asintroduced with the composition according to the invention effect adown-regulation of the expression of a target gene to an extent whichnow allows for a use of the mechanism of the RNA-interference in thetherapy, diagnosis and/or prevention of diseases or diseased states thatare caused by the expression of a nucleic acid of a pathogenic organismor by the increased or undesired expression of an endogenous gene.Thereby, it was a completely surprising finding that, using thecomposition according to the invention, RNA-molecules with a definedsecondary structure could be introduced into a cell, wherein theRNA-molecules as introduced function as a substrate for theRNAi-biogenesis apparatus of the target cell because of theirconformation, so that an efficient down-regulation of the expression ofa target gene becomes possible. Thus, with the composition according tothe invention, si/miRNA-precursor-molecules such as dsRNA and shRNA canbe introduced into a target cell in such a way that they are recognizedas a substrate by the si/miRNA generating enzyme complexes in the cell,and are efficiently processed into effector molecules of the sequencespecific down-regulation of the expression of a target gene. It wasfurthermore surprising that even VLP that are derived from DNA-virusescan be used for the transfer of siRNA or miRNA, respectively, into atarget cell, or the precursor molecules thereof, such as dsRNA or shRNA.

An RNAi-inducing molecule shall furthermore also include modifiedRNA-molecules that include 5′-prime and/or 3′-prime modifications, suchas fluorescence groups and/or 3′-dTdT-overhangs, and affect adown-regulation of the expression of a gene of interest in a eukaryoticcell.

According to the present invention, an RNAi-inducing molecule shallfurthermore mean those RNA-molecules that include analogs of one orseveral ribonucleotides in the nucleotide sequence and affect adown-regulation of the expression of a gene of interest in a eukaryoticcell. These ribonucleotide-analogs can, for example, increase thestructural stability of the RNA-molecule or the stability againstribonucleases. Ribonucleotide-analogs are known to the person of skilland, in comparison with the original RNA-molecules, are modified by basemodifications, sugar modifications, e.g. modifications of the 2′-OHgroup of ribose, and/or phosphate backbone modifications.

Therefore, within the VLP a single type of an RNAi-inducing molecule,i.e. siRNA, dsRNA, shRNA or miRNA or their precursor molecules or DNAencoding can be packaged. Nevertheless, also different types of anRNAi-inducing molecule can be included in a VLP. The RNAi-inducingmolecules of the composition according to the invention can be directedagainst one or several target genes and/or against the same or differentsequences of a single target gene.

In this context, the term “directed against a gene” shall mean that anRNAi-inducing molecule contains the sequence information for a sequencespecific degradation of an RNA-molecule, preferably an mRNA-molecule ofa target gene.

According to the invention, RNAi-inducing molecules can be directedagainst one or several genes whose expression shall be down-regulated.Preferably the RNAi-inducing molecules of the composition according tothe invention are directed against actively expressed genes, whoseexpression correlates with a pathologic state.

Particularly preferred, the composition according to the inventioncontains RNAi-inducing molecules that are directed against at least onegene of a pathogen, e.g. a pathogenic virus. Furthermore, thecomposition according to the invention can contain RNAi-inducingmolecules that are directed against at least one endogenous gene,wherein the expression of the endogenous gene and/or the increasedexpression of the endogenous gene correlates with a pathologic state.Examples for such cellular endogenous genes are, for example,tumor-associated genes, autoimmune-associated genes, metabolicdiseases-associated genes, and in particular genes that are associatedwith neurodegenerative and general neural disease. Additional examplesare endogenous genes in the context of infectious diseases (hostfactors) and genes in the context of dystrophy and progeroid diseases(allele specific, e.g. emerin, lamin A/C, FACE-1, etc.).

The VLP of the composition according to the invention can be composed ofone type of a capsid protein or of several different capsid proteins.Preferably, the composition according to the invention contains a VLPthat is composed of one type of a capsid protein. Particularlypreferably, a VLP is used whose capsid proteins have the inherentproperty to assemble one with another into a VLP under suitableconditions both in vivo as well as in vitro, i.e. no additionalauxiliary factors are required for the formation of the VLP from themonomeric proteins.

The ratio of the mass of VLP to RNAi-inducing molecule is usually foundin a range between 1:100 to 100:1, preferably 1:50 to 50:1, particularlypreferred 1:20 to 20:1, and most preferred in a range of 1:1 to 20:1.

Preferably, a VLP is used which is free from other components of theauthentic virus, such as, for example, authentic viral nucleic acids.Particularly preferred is the use of a VLP which is composed of thecapsid protein VP1 of the human JC-virus (JCV). JCV belongs to the genusof polyomaviruses, whose viral genomes are present inside the capsid inthe form of double-stranded DNA.

In a particular embodiment, the VLP is composed of recombinantlyproduced capsid protein. The term “capsid protein” according to thepresent invention, in addition to the capsid protein of the wild typestrain of the respective virus, such as, for example, wild type-VP1,also comprises modified forms of the capsid protein, i.e. proteins thatdiffer from wild type-capsid protein by mutations, such as, for example,substitutions, insertions, and/or deletions. For producing recombinantVP1 preferably a nucleic acid is used that has the sequence as shown inSEQ ID NO. 1, a sequence corresponding to this sequence in the contextof the degeneration of the genetic code, or a sequence hybridizing withthe sequence under stringent conditions, whereby the nucleic acidsequence or a recombinant vector containing this sequence is introducedinto a suitable host cell, the host cell is cultured under conditionswhereby an expression of the nucleic acid sequence takes place, and theprotein is isolated from the cell or the cellular supernatant. Stringenthybridization conditions are preferably defined according to Sambrook etal. (1989) Molecular Cloning. A Laboratory Manual, Second Edition, ColdSpring Harbor Laboratory Press, and comprise a washing step of 30 min in0.1×SSC, 0.5% SDS at 68° C.

The amino acid sequence encoded by the nucleic acid according to SEQ IDNo.1 is shown in SEQ ID No. 2. In the context of the present invention,preferably a VP1-polypeptide is used containing SEQ ID No. 2 or an aminoacid sequence being identical to said sequence to at least 70%,preferably to at least 80%, particularly preferred to at least 90%, andmost preferred to at least 95%, wherein the identity is determined overthe whole region of SEQ ID No. 2.

In a further preferred embodiment a VP1 protein is used, wherein theamino acid sequence was modified in the N-terminal region, for examplein the region of the 25 N-terminal amino acids. In doing so, preferablya heterologous nuclear localization signal is introduced into the aminoacid sequence of VP1. Preferred nuclear localization signals contain theamino acid sequence CPGAAP X₁X₂P, wherein X₁ and X₂ mean arbitrary aminoacids and preferably in each case mean K, and, for example, are based onthe nuclear localization signals of SV40 or BKV. The amino acidsequences of particularly preferred nuclear localization signals areshown in FIG. 4A.

The nucleic acid sequence encoding for a preferable modified VP1 protein(VP1-Mut2) is shown in SEQ ID No. 3. The corresponding amino acidsequence is shown in SEQ ID No. 4. One object of the present inventionthus is a modified JCV-VP1 protein containing a heterologous nuclearlocalization signal, preferably as mentioned above, a nucleic acidencoding it, and a VLP₁ containing at least one accordingly modified VP1protein, wherein said VLP optionally can contain active agents, inparticular nucleic acids, but also other molecules.

Depending from the host/vector system as used, the isolation ofrecombinant capsid proteins either takes place directly from the hostcells and/or from the cell culture supernatant. The advantage of therecombinant method primarily lies in the fact that VLPs can be obtainedin a simple fashion with high purity and in large amounts. In practice,in the recombinant synthesis of VP1 the use of baculoviruses togetherwith insect cells, e.g. with the insect cell line Sf 158, has proven itsworth as the expression system.

The suitability of the VP1-VLPs as a cell specific DNA-transport andtransduction system for cells of renal and neuronal origin was alreadyshown in DE 101 31 145.1. This document furthermore describes a methodfor the modification of the VP1-VLPs in order to systematically modifytheir cellular tropism, so that defined target cells and tissues can beselectively transduced.

Surprisingly, it was now found that also RNAi-inducing molecules, inparticular dsRNA, shRNA, miRNAs, siRNA or precursor molecules thereof,can be packaged inside a VLP of the JC-virus without changing thestructure of these molecules. It was found that RNAi-inducing moleculesthat induce RNAi in the target cells are sufficiently protected insideof the VLPs both against degradation and structural changes. The termtarget cells shall mean eukaryotic cells, and preferably the cells of amulti-cellular organism, in particular mammalian cells, including cellsof human origin.

For introducing RNAi-inducing molecules into cells corresponding to thenatural host spectrum of the virus, whose capsid protein is a componentof the composition according to the invention, preferably a VLP is usedwhose capsid protein corresponds to the wild type capsid protein. Forexample, the host spectrum of the JCV comprises cells of the neuraltissue and cells of neurally-related tissues, such as, for example,oligodendrocytes, astrocytes, and glial cells. When RNAi-inducingmolecules shall be introduced into these cells, the compositionaccording to the invention preferably contains a VLP which is composedof the wild type-VP1 capsid protein of the JC-virus.

For providing RNAi-inducing molecules for cells that do not correspondto the natural host spectrum of the virus whose capsid protein is acomponent of the composition according to the invention, preferably aVLP is used whose capsid protein is modified when compared to the wildtype capsid protein. The use of modified VLPs in the compositionaccording to the invention preferably allows for the treatment ofdiseases that are limited to particular types of cells or to particulartissues, respectively. Particularly preferred, the composition accordingto the invention consists of a VLP of the JC-virus, wherein at least onecapsid protein of the VP1-VLP is modified when compared with the wildtype-VP1.

Modifications on the one hand comprise modifications in the amino acidsequence of the wild type capsid protein. In particular insertions,deletions, substitutions and/or fusions with other amino acid sequencesbelong to this group, with the provisio that the inherent property ofthe capsid proteins for self assembly, i.e. for forming VLPs, does notget lost. Thus, the VLP of the composition according to the inventioncan include one or several additional heterologous proteins or parts ofthe protein in the capsid structure in form of a fusion protein. Thismeans that a heterologous protein or a heterologous part of the proteinis anchored in the capsid structure, wherein preferably at least a partof this protein is accessible from the outside. VLPs that are composedof such fusion proteins, because of the fusion part, can interact with aspecific surface receptor of the intended target cell. In this way thespecificity of the interaction with the intended target cells can beassured and can be adjusted to a multitude of cell types in dependencyfrom the use. It is also possible to limit the tropism of the VLPs todifferent cells or tissues by a targeted modification of the capsidproteins.

An additional possibility in order to direct the tropism of the VLPstowards a defined type of cell consists in a chemical modification ofthe VLPs of the composition according to the invention. A chemicalmodification of the VLPs allows for a flexible use of the compositionaccording to the invention as a transfer system for RNAi-inducingmolecules for particular cells or tissues, respectively. For thetargeted modification of the target cell specificity of the VLPs,conjugates of VLP and a cell type specific ligand have proven to beadvantageous. In a preferred embodiment, at least one ligand isassociated with the VLP. Thereby, the ligand basically can be anysubstance.

The ligand, for example, can be a target cell-specific group, e.g. abinding partner for a cell surface receptor. Suitable examples forbinding partners are natural ligands or synthetic analogs thereof,wherein high molecular weight ligands, such as proteins, e.g.transferrin, antibodies or sugars, such as mannose, but also lowmolecular weight synthetic ligands, e.g. the tripeptide-motif R-G-D(Arg-Gly-Asp), can be used. Alternatively or additionally, also alabeling group, e.g. a group which can be detected using suitabledetection methods, such as, for example, a fluorescent labeling group orbiotin, can be used as a ligand. Furthermore, the ligand can also be aneffector group, e.g. a cytotoxic group. Of course, also combinations ofseveral ligands, in particular combinations of the before-mentionedligands, can be used.

The interactions between ligand and the capsid protein of the VLP arepreferably mediated by chemical anchoring groups. Thereby, in particularthe loading of the capsid protein with cationic polymers as anchormolecules for cell specific ligands has proven to be suitable.

Specific examples for cationic polymers are essentially basic aminoacid-based polymers, such as, for example, polylysine, in particularpoly-L-lysine, etc. Additional specific examples for suitable cationicpolymers are polyalkylene amine, polyalkylene imine, preferablypoly-C₂-C₄-alkylene imine, in particular polyethylene imine (PEI), pAMAM(polyamidoamine)-dendrimers and fractionated dendrimers, as well ascationically modified polyethylene glycol. Polyethylene imine is aparticularly preferred cationic polymer in the sense of the presentinvention, since it is non-toxic and has a high density of positivecharges. PEI is furthermore able to effect a pH-dependent structuralchange after uptake into the cells, leading to a destabilization ofendosomal and lysosomal cell compartments and thus to a support of therelease of RNAi-inducing molecules into the cytoplasm. This process issupported by the pronounced buffer capacity of the imino groups that areprotonated in the lysosomes after an acidification and then lead to anosmotic rupture of the vesicular membrane.

The weight ratio of VLP to cationic polymer in the conjugates can bevaried within broad ranges. Thus, weight ratios of 5:1 to 1:10 haveproven to be suitable, wherein weight ratios of 2:1 and 1:5 areparticularly preferred in order to allow for an optimal binding.

Methods for producing conjugates of VP1-VLP and cationic polymers areknown from DE 101 31 145.1.

In an additional preferred embodiment, heterologous binding partners orligands, respectively, e.g. polypeptides or labeling groups, can becoupled directly and with a controllable stoichiometry to the VLPs. Theexample of a heterobifunctional protein-protein linker is shown in FIG.5. Here, the amino group of the lysine residue at the outside,preferably of K60 and/or K164, is used in order to bind the linker (herea PEO-maleimide linker) to VP1. Ligands can bind through a cystineresidue, e.g. a carboxy-terminal cystine residue, to the second activesite of the linker, and give a stable VP1-ligand conjugation which canspecifically deliver a VLP-loading into the ligand-specific type ofcell.

Thus, another object of the invention is a JCV-VP1 capsid protein towhich at least one heterologous binding partner, e.g. a polypeptide, isbound through the amino acid residues K60 and/or K164.

An object of the present invention are furthermore compositionscomprising

(i) a conjugate of a virus-like particle (VLP) being composed of severalmolecules of at least one viral capsid protein and at least one celltype specific ligand, wherein VLP and ligand are connected to each otherby anchoring groups, such as, for example, cationic polymers or throughheterobifunctional linkers, and

(ii) RNAi-inducing molecules, that are incorporated into the conjugateof VLP and ligand.

Preferably a VLP is used which is derived from the capsid protein VP1 ofthe human polyomavirus JC. Preferably, as RNAi-inducing molecules thoseas described above are used.

For producing a composition according to the preamble of claim 1, theRNAi-inducing molecules, and optionally additional active substances aswell as carriers, auxiliary agents, and/or additives are added to thecapsid proteins in the desired amounts or concentration, respectively,before and/or during the assembly. In doing so, VLPs can be generatedcontaining RNAi-inducing molecules within the particles. Preferably, theloading of the VLPs with RNAi-inducing molecules takes place during theassociation of the capsid proteins into the VLP. The packaging of theRNAi-inducing molecules can both occur in vitro as well as in vivo,wherein the incorporation of the RNAi-inducing molecules in das VLPpreferably takes place under in vitro conditions. The incorporation ofRNAi-inducing molecules into the inside of the capsid coating can takeplace, e.g. by dissociation (de-assembly) of the capsid coating and asubsequent re-assembly in the presence of the RNAi-inducing molecules orby osmotic shock of the VLPs in the presence of the RNAi-inducingmolecules. Furthermore, a target cell specific group that is able tobind with receptors on the surface of a target cell can be bound to theVLP loaded with RNAi-inducing molecules as described above. Theconditions for the loading of the VLP are each to be chosen in a waythat a degradation or a structural change, respectively, of theRNAi-inducing molecules is avoided.

During packaging, the ratio of capsid-protein-monomer to RNAi-inducingmolecules can vary over a brad range, depending from the number of thecapsid-proteins per VLP and the size of the molecules to be packaged.The mass ratio of capsid protein to RNAi-inducing molecule usually isfound in a range of between 1:100 to 100:1, preferably 1:50 to 50:1,particularly preferred 1:20 to 20:1, and most preferred about 1:1 to20:1.

Against the background that the capsid-protein is produced recombinantlyand separately from the RNAi-inducing molecules in large amounts andwith high purity, and that the packing of the nucleic acids, in contrastto the retroviral, adeno-associated or adenoviral vectors, does not takeplace in packaging cell lines, contaminations with viral nucleic acidsand the potential danger of the generation of infectious viruses due torecombination events can be avoided. Since furthermore the packing ofRNAi-inducing molecules and the loading of the VLPs with cell specificligands takes place under defined in vitro conditions, theVLP-RNAi-transfer system, and here in particular the VP1-VLP-transfersystem, represents a biologically safe platform technology combining theadvantages of viral and non-viral systems, nevertheless, withoutexhibiting the disadvantages thereof. Thus, the VLPs of the compositionaccording to the invention are particularly characterized by the factthat they are free of nucleic acids of the original virus. Such VLPs, inparticular VLPs of recombinant VP1-molecules, are described in WO97/19174.

The composition according to the invention can be used in order tospecifically introduce RNAi-inducing molecules into any type of cellsboth in vivo and in vitro. Thereby, the targeted transfer of functionalRNAi-inducing molecules within a multi-cellular organism leads to alocally limited down-regulation of the expression of a gene of interestby means of RNAi. Thus, when using the composition according to theinvention, for example the increased expression of an endogenous genecan be transiently down-regulated, without the existing danger of amodification of the genome of the target cell. Nevertheless, by means ofRNAi it is also possible to permanently integrate the geneticinformation for the targeted, i.e. sequence specific, degradation ofRNA, in particular mRNA, into a target cell. Furthermore, thecompositions according to the invention can be used in order todown-regulate the expression of undesired genes, for example as theresult of a transposition of DNA-segments or a viral infection, in acell type-specific manner. In particular, the composition according tothe invention can be used in order to down-regulate the expression of atleast one gene that correlates with a pathological state.

A composition according to the invention can be used in order to treatchronic diseases or their symptoms, respectively. In this case,RNAi-inducing molecules can be used, for example, in the form ofDNA-constructs that effect a permanent provision of siRNA or theirprecursor molecules in a target cell. Furthermore, it now becomespossible using the compositions according to the invention, totransiently establish cell type-specific gene therapies, for example fora treatment of acute infections both in the veterinary as well as inhuman medicine. The amounts of the composition according to theinvention to be administered depend, amongst others, from the kind ofdisease, the severity of the symptoms, and from the scope of the cellsthat are affected.

The composition according to the invention can be administered locallyor systemically in accordance with known methods for the application ofVLPs.

Thus another object of the present invention is a method for introducingRNAi-inducing molecules into a target cell, comprising the steps

(i) Assembly of the viral capsid proteins into VLPs in the presence ofthe RNAi-inducing molecules, and

(ii) Contacting the VLP loaded with the RNAi-inducing molecules with thetarget cell under conditions whereby an uptake of the RNAi-inducingmolecules into the target cell can occur.

For modifying the target cell specificity furthermore one or more targetcell specific groups can be bound to the VLP as obtained in step (i)that can bind with receptors on the surface of a target cell. The methodaccording to the invention, amongst others, can be used for adown-regulation of at least one gene of interest in a target cell.

Any eukaryotic cell can be used as a target cell. Preferably, theeukaryotic cell is a mammalian cell, and in particular of human origin.Using a composition according to the preamble of claim 1, it is possibleto introduce RNAi-inducing molecules both into cells that are present intheir natural environment as well as into cells that were isolated fromtheir natural context.

If the target cells, into which the RNAi-inducing molecules shall beintroduced, do not correspond to the natural host spectrum of theviruses from which the VLPs that are used in the method according to theinvention are derived from, the cell type-specificity of the VLPs can bemodified (“re-targeting”) before, during or after the loading withRNAi-inducing molecules and, optionally, additional active agents,through complexing of the capsid proteins with ligands as describedabove. Thereby, advantageously those ligands are selected that can tospecifically bind with receptors that are exposed on the cellularsurface of the target cells. Alternatively, VLPs can be used for thisconsisting of capsid proteins which in their amino acid compositioninclude a heterologous protein, which mediates a targeted transfer ofRNAi-inducing molecules, and optionally additional active agents, due toits ability to bind to specific receptors on the outer surface of thecell of the target cells.

A further object of the present invention is a pharmaceuticalcomposition comprising VLPs as described above that includeRNAi-inducing molecules as described above, for the diagnosis,prevention, and/or treatment of diseases or disease states that arecaused by the expression of a foreign nucleic acid, for example anucleic acid of a pathogenic organism, in particular a pathogenic virus,or by the increased or undesired expression of an endogenous gene.

The present invention furthermore relates to a test kit for introducingRNAi-inducing molecules into any kind of cells or tissues, respectively,comprising VLPs as described above.

Yet another object of the invention are VLP-compositions as indicatedabove containing other kinds of nucleic acids, e.g. immune-stimulatorynucleic acids, optionally in combination with polypeptide- orpeptide-immunogens, aptamers or siDNA-molecules. Further suitable drugsare polar cytostatic agents or toxins.

In addition to the afore-mentioned RNAi-inducing molecules, inparticular in the context of infectious retroviral diseases (e.g. HIV-1)also other nucleic acids have to be mentioned as additional therapeuticand prophylactic VLP loadings. For prophylactic uses, immune-stimulatorysequences (ISS) shall be mentioned here, optimally in combination withimmunogens from the respective retrovirus (e.g. env-components fromHIV-1). In addition, for a therapy a virus inhibition shall be achievedthrough several non-RNAi inducing nucleic acid sequences. Thesemolecules can be selected from inhibitory DNA and RNA aptamers, as wellas from so-called siDNAs that can destroy the genome of retrovirusesbefore the integration thereof into the host genome by a prematureactivation of the enzyme RNAse H. (Matskevich et al., Aids Res & HumanRetroviruses 22 (2006), 1220-1230; Matzen et al. Nature Biotechnology 6(2007)). Regarding the inclusion of such nucleic acids into VLPs,reference shall be made to the description in connection with RNAimolecules.

The invention is now further explained by the following examples as wellas the attached figures and the sequence listing.

EXAMPLE 1

Materials and methods

Construction and Synthesis of siRNA-Molecules

RNA-oligonucleotides were chemically synthesized and obtained fromDharmacon (Lafayette, Colo.). All siRNA-molecules contained3′-dTdT-overhangs. Fluorescence labels were coupled to the 5′-end of thesense-strand of the siRNA-molecules, in order to not impart theirfunctionality. Nucleotides (dNTPs) for a PCR were obtained fromBoehringer (Mannheim, Germany), PCR-primers and DNA-fragments forproducing shRNA by means of in vitro-transcription were provided by NAPS(Gottingen, Germany). Double-stranded RNA having a length of 27nucleotides (27mer dsRNA) were chemically synthesized and provided byIBA (Gottingen, Germany).

TABLE 1 siRNA-molecules, target genes, positions, modificationsNucleotide Modifi- siRNA Target gene position cations Notes siLamA1Human lamin 608-630 A/C siLamA2 Human lamin 672-694 A/C siL27AC Humanlamin 670-697 Blunt-ended A/C 27mer dsRNA siLamA3 Human lamin A1919-1941 siLamA-F Human lamin Fluorescent dye A/C (fluorescein) iscovalently coupled to the 5′-end of the passenger strand siEg5-F HumanEg5 1547-1569 Fluorescent dye (rhodamine red) is covalently coupled tothe 5′-end of the passenger strand siEme-1 Human emerin 628-640 siEme-2Human emerin siEme-3 Human emerin siGL2 Firefly 153-175 Non-relatedluciferase control

Antibodies and Indirect Immunofluorescence Microscopy

Transduced cells were treated with −20° C. cold methanol with VLPs 44hours after the treatment. As primary antibody, a mouse-anti-laminA/C-antibody (clone 636.23), a mouse-anti-emerin-antibody (Novagen), anda mouse-anti-α-tubulin-antibody (D1H, Sigma, Germany) were used. Assecondary antibody, rhodamine- or fluorescein-conjugated goatanti-mouse-IgGs were used. After the fixation, the cells that werewashed with PBS were incubated at 37° C. in a humidity chamber for onehour with a first antibody. Subsequently, the cells were washed threetimes with PBS, and fluorescent secondary antibodies were added for onehour at 37° C. Unbound antibodies were removed by washing three timeswith PBS, and the DNA was then visualized with 2 μM Hoechst 33342 dye(Hoechst, Germany). For this, the cells were fixed with Mowiol (Hoechst,Germany) on glass slides.

Quantitative Western Blot-Analysis

An SDS-gel electrophoresis was performed according to standardprotocols. The proteins were separated by means of standard-SDS-gelelectrophoresis, and transferred onto a nitro-cellulose membrane usingthe semi-dry-transfer method. Membranes were blocked in TBST (20 mMTris-HCl, 150 mM NaCl, 0.2% Tween 20, pH 7.4), wherein the TBSTcontained 5% of skim milk powder. Antibodies against lamin A/C, emerinor vimentin were also diluted in TBST, wherein the TBST contained 2.5%of skim milk powder. The accordingly diluted antibodies were incubatedwith the membrane for 1 h at room temperature. The vimentin proteincontent was determined in order to allow for an analysis of identicalamounts of protein in the Western blot. The membranes were washed twicewith TBST, and once with TBST plus 0.5% Triton X-100. Affinity purifiedhorseradish-conjugated porcine anti-mouse immunoglobulins were obtainedfrom Dako (Copenhagen, Denmark). They were diluted 1:10.000 in blockingbuffer containing 2.5% of skim milk powder, and incubated with themembrane for 2 h at room temperature. The bands were detected using theECL-kit (Amersham Biosciences), and quantified on a Lumilmager(Boehringer/Roche, Germany).

Cells

TABLE 2 Cell lines as used in this study Cell line Origin (source) HeLaSS6: Human cervical carcinoma (ATCC and Gey et al., 1952) MCF-7: Humanbreast carcinoma (ATCC and Soule et al., 1973) 293T Human embryonickidney (ATCC) COS-7: Kidney fibroblasts of the African Green Monkey(ATCC) Human Chondrocytes Glioma SW103 Human glioblastoma cell line(ATCC) HeLa S3 Human cervical carcinoma adapted for growth in suspensionSupT1 Human T-cell line (ATCC)

Adherent cells (i.e. HeLa SS6, MCF-7, 293T. COS-7, chondrocytes andglioma SW103) were cultured in DMEM, which was supplemented with 10%fetal calf serum (FCS) and antibiotics (penicillin and streptomycin,pen/strep). Cells in suspension (i.e. HeLa S3 and SupT1) were culturedin RPMI-1640 high glucose-medium, which was supplemented with 10% FCSand pen/strep.

Production of the VLPs and Loading

The VP1-protein of the polyoma-JC-virus was expressed in insect cells(SF) using a baculoviral system. Secreted protein was isolated from themedium supernatant using gradient centrifugation or ion-exchange-FPLC.

Purified VP1 was present in the form of pentamers and capsids of higherorder, therefore, before loading with a nucleic acid these first had tobe de-assembled using a de-assembly buffer (10 mM Tris, pH 7.5, 10 mMEGTA, 150 mM NaCl, 5 mM DTT). The loading of the VLPs throughre-assembly took place through dialysis of the VP1/nucleic acid mixtureagainst re-assembly buffer (10 mM Tris, pH 7.5, 1 mM CaCl₂, 150 mM NaCl)in a micro dialysis setting with an exclusion size of 3.5 kDa over nightat 4° C. The standard ratio of DNA to VLP was 1:10 (e.g. 500 ng wereadded to 5 μg VLP). For the subsequent re-targeting, the re-associatedVLPs were mixed with PEI-Tf in a ratio of 1:5 (PEI to VLP, e.g. 1 μg PEIis added to 5 μg VLP).

Transfection/Transduction

24 hours before the treatment with siRNA-loaded VLPs, the cells wereeach plated in 24-well-plates at 50.000 to 100.000 cells/ml. In case ofcells cultured in suspension (i.e. SupT1- and HeLa S3-cell lines), theculture medium was supplemented with 0.5 ng/ml desferiox-amin, in orderto stimulate the transferrin metabolism, and to increase the density ofthe transferrin receptor on the cellular surface. Immediately before thetreatment with VLPs, the stimulation medium was replaced by normalculture medium, in order to avoid cytotoxic side-effects of the agent.

Results

Introduction of DNA and siRNA into Human Glioma Cells

siRNA loaded VLPs were added to the culture medium of human glioma SW103-cells. One hour after the treatment, fluorescently labeled siRNAsthat were directed against human lamin A/C (siLamA-F) could be observedin the cytoplasm of the glioma cells (see FIG. 1). The specific uptakeof exclusively VLP-packaged siRNA was confirmed by a treatment ofcontrol cells with naked siRNA, and empty VLPs. 24 hours after theVLP-transduction the cells were examined in view of the RNA-interferingeffects by means of indirect immunofluorescence microscopy and WesternBlot-analysis. The amounts of the target protein lamin A/C wereeffectively down-regulated in the cells treated with siLamA-F-VLP,whereas this could not be observed in the control cells (FIG. 1).

The introduction of siRNA-molecules into glioma SW103-cells was alsoused in subsequent experiments, including the re-targeting of the VLPsthrough complexing thereof with PEI-Tf, as a quality control for thepackaging of nucleic acids into VLPs.

RNA-Interference in Adherent Cells, Mediated by siRNA-Loaded VLPs BeingComplexed with PEI-Tf

The VLPs loaded with siRNA-molecules were added to the culture medium ofdifferent human cell lines. Several experiments were performed on HeLaSS6-cells. The cells were plated 24 hours before the treatment with theVLPs. The examinations occurred 24 or 48 hours after this treatment.

HeLa-Cells

1. Dosage Dependency and Functional RNA-Interference byPEI-Tf-VLP-Mediated Introduction of siRNA-Molecules.

HeLa-cells were plated in 24-well-plates in a density of about 75.000cells/well, and treated with 1 or 5 μg VLPs after 24 hours. In order todetermine the amount of siRNA-molecules that was required for afunctional and effective RNA-interference, the VLP were loaded with 50nM or 3 μM siRNA in reassembly buffer. Empty VLPs, VLP which were loadedwith non-related siRNA-molecules, and siRNA-molecules that were onlycomplexed with PEI-Tf served as controls. PEI-Tf were added in a ratioof 1 to 5 (1 μg Pei-Tf:5 μg siRNA-VLP) to the loaded and re-assembledVLP, in order to allow for the uptake into the cells by means of thetransferrin receptor. For an efficient RNA-interference in about 100.000cells of each well of a 24-well-plate, it was necessary to treat thesewith 5 μg VLP, wherein the VLPs were loaded with 3 μM siRNA (FIG. 2).The transduction of siRNA with VLP that were loaded with 50 nM siRNA,merely led to a small decrease of the target protein lamin A(/C). Theuptake of siRNA was confirmed by means of the transduction offluorescence-labeled siRNA siLamA-F, and the effects of thedown-regulation were examined on the protein level by means ofquantitative Western Blot-analysis and indirect immunofluorescencemicroscopy. The transduction of cells with empty Pei-Tf-VLP or with VLPcontaining a non-related siRNA did not lead to a decrease of the laminA(/C)-protein content. PEI-Tf complexed siRNA without VLPs caused a weakinhibition of the lamin A(/C)-expression, wherein, nevertheless, thedown-regulation was limited to 15-20%, whereas siLamA-PEI-Tf-VLPs causeda nearly complete down-regulation (“knockdown”) of the target protein,when used in the suitable concentration (Fig. HeLaA). Three differentsiRNA-molecules that were directed against lamin A/C, one of which wasfluorescence-labeled, were examined on HeLa-cells in order to visualizethe uptake of the VLPs into the cells and into the cytoplasm. AllsiRNA-molecules led to an effective down-regulation of the targetprotein expression, when they were administered to the cells in the formof PEI-Tf-VLP.

2. Non-Classical 27mer dsRNA-Molecules were Successfully Used for aDown-Regulation

Furthermore, a non-classical siRNA, i.e. siL27AC, which consisted of a5′-phosphorylated dsRNA having a length of 27 nucleotides without3′-overhangs, was transduced into HeLa-cells, which caused an efficientdown-regulation of the expression of the lamin A/C-protein. Thus, thecomposition according to the invention also makes it possible tointroduce substrates for the endonuclease Dicer into the cytoplasm of atarget cell by loading of the VLP with a 27mer dsRNA, in order to makeit available for the RNA-interference machinery of the cell.

3. PEI-TF VLPs were Used for the Introduction of Active siRNA-Moleculesinto Breast Vancer Cells

A second set of three different siRNA-molecules that were directedagainst the human emerin-gene was transduced into human breastcancer-MCF-7-cells, as described above. A quantitative WesternBlot-analysis showed that all three siRNA-species that were used inthese experiments successfully caused a down-regulation of the targetgene (FIG. 2A). These results emphasized the broad applicability of theVLPs in view of an efficient transfer of siRNA-molecules which aredirected against alternative target genes in different types of cells.

Additional cell lines and information can be taken from Table 3 thatreflects a summary regarding nucleic acid transfer experiments usingVLPs in different cell lines.

RNA-Interference in Non-Adherent Cells, Mediated by siRNA-Loaded VLPsthat are Complexed with PEI-Tf

Human SupT1 T-cells were cultured in suspension, and plated out 24 hoursbefore the treatment with VLPs. In order to induce the cellular energymetabolism and to increase the density of the transferrin receptor onthe surface of the cells, 15 nM desferrioxamine was added to the culturemedium. Immediately before the treatment with VLPs, the medium wasreplaced by standard culture medium, and the VLPs were added in theamounts as given above. SupT1-cells were transduced with VLP containingsiRNA-molecules that were directed against endogenous human emerin, anon-related siRNA (GL2), or no siRNA (FIG. 3). The same VLPs were usedas a control with and without PEI-transferrin. As an additional control,cells were subjected to PEI-Tf complexed siRNA-molecules, wherein thisRNA was not incorporated into VLPs. In order to show the uptake of thesiRNA-molecules into the cytoplasm of the cells, a fluorescence-labeledsiRNA was used. Using confocal microscopy, the homogenous dispersion ofthe fluorescent siRNA in the cytoplasm of SupT1-cells was shown.Sections along the X-axis of such a cell are shown in FIG. 3A. Theeffective down-regulation of the target gene expression by means ofVLP-introduced siRNA was confirmed using indirect immunofluorescencemicroscopy (FIG. 3B) and Western Blot-analysis (FIG. 3C). The resultsshow a very efficient down-regulation of the emerin-gene expression innearly 100% of the cells as treated, whereas the treatment withnon-related siRNA did not influence the content of emerin. The WesternBlot-data showed that a sufficient down-regulation of the emerin couldonly be achieved, when the cells were treated with siEme-loadedPEI-Tf-complexed VLPs, whereas a PEI-Tf-complexing alone does not leadto a measurable down-regulation of the protein.

Likewise, a VLP-mediated siRNA-uptake was successful, when HeLa S3-cellswere used. These cells are adapted to the growth in suspension (data notshown).

TABLE 3 Summary of the experiments, cell lines, siRNA-molecules, RNA-and DNA-constructs, and experimental results. SiRNA/target Uptake/Experiment cell line cell knock-down Note/Explanation VLP-mediated HeLaSS6 siEg5-F Yes siRNA-molecules cellular uptake (human) siLamA-F weresuccessfully of fluorescent COS-7 siEg5-F Yes introduced in a siRNAmolecules (African Green siLamA-F dosage dependent into adherent Monkey)manner into the cells Chondrocytes siEg5-F Yes cytoplasm in >90% (human)of the cells as was shown by immuno- fluorescence microscopy, atreatment with PEI alone is not sufficient for an effective introductionof RNAi-inducing molecules into a target cell. RNAi by means HeLa SS6Lamin A/C Highly efficient siRNA-molecules of VLP- (human) (threedifferent knock-down (>90%) as introduced by introduced siRNA- means ofVLP siRNA molecules, one caused a down- molecules chemically regulationof the modified, i.e. expression of a siLamA1. target gene, whichsiLamA2, is comparable or siLamA-F) better than a siEg5-F Highlyefficient classical siRNA- knock-down transfection (e.g. COS-7 siEg5-FHighly efficient by cationic (African Green introduction and liposomesor Monkey) highly efficient electroporation). A knock-down knock-downwas confirmed by means of IIF and Western Blot. In case of the down-regulation of Eg5, the expected secondary effects were found, i.e. amitotic arrest could be observed in all cells. Chondrocytes Lamin A/CKnock-down The cells did not (human) (two different in only a few cellsproliferate, which siRNA- indicates that the molecules, experimentalsiLamA2, timeframe was siLamA-F) insufficient for a down-regulation ofthe protein lamin A, since this protein has a long half-life (adegradation requires one mitosis) MCF-7 siEme1, Efficient (human mammasiEme2, knock-down, carcinoma) siEme3, documented siLam A1 by WesternBlot 293T siEme1 Efficient (human knock-down, embryonic documentedkidney) by Western Blot RNAi by means HeLa SS6 siL27A Efficient 27mersof blunt- of 27mer (human) knock-down ended dsRNA- dsRNA- (not shown inmolecules were molecules IIF and Western successfully Blot) transducedand processed by Dicer. Cells in SupT1 siLamA-F Uptake (nearlySupT1-cells require a suspension siEme1 100%) and pre-treatment withfunctional desferrioxamine. RNA- in order to increase interference thedensity of the against emerin transferrin (>85% down- receptor.regulation) was shown both in IIF and Western Blot. HeLa S3 siLamA-FUptake was shown Linear pol SupT1, glioma pol II-eGFP IntroductionII-eGFP- SW103 linear DNA into nearly all expression (2.4 kb) cells,construct accordingly, eGFP was expressed in both cell lines PackagingIn vitro study VLP loaded After reassembly, efficiency with siRNA >80%of the VLPs were loaded with si- molecules Cytotoxic All cell All siRNA,in No effects on studies lines/animals particular for a the vitality oftherapy the cells was observed

EXAMPLE 2

A modified protein VP1-Mut2 was produced that compared to the wild typesequence had a modification in the amino-terminal region. Because ofthis modification, the amino acid sequence of a heterologous nuclearlocalization signal based on the sequence of the viruses SV40 or BKV wasintroduced. The sequence of the heterologous nuclear localization signalis shown in FIG. 4A.

The chimeric protein VP1-Mut2 was tested for the ability to form intactVLPs, which was confirmed by electron-microscopy imaging. Furthermore,different types of cells were transduced with DNA-loaded VP1-Mut2 VLPs,and in doing so the chimeric form showed at least an equal (COS-7 kidneycells) or up to five-fold increased (SVG glial cells) transductionefficiency. The results are shown in FIGS. 4B and 4C.

EXAMPLE 3

Using a heterobifunctional linker, ligands can be bound directly to theVP1-protein. A preferred embodiment for such a coupling method isdepicted in FIG. 5.

DESCRIPTION OF THE FIGURES

FIG. 1: Efficient and functional introduction of siRNA-molecules and DNAinto glioma SW 103-cells

A) Cells were treated with siLamA1 or siGL2 siRNA-loaded VLPs, andexamined 44 hours after the VLP-treatment by means of indirect immunofluorescence (IIF). The left field shows a group of cells that weretreated with siLamA1-VLP, wherein the cells show a nearly completedown-regulation of the target protein (top). The control cells that weretreated with the non related control-siGL2-VLP showed a normal laminA/C-content, wherein lamin A/C is present in the nuclei of the cells.The DNA was stained with Hoechst 33342.

B) The observations from the direct immuno fluorescence microscopy wereconfirmed with a Western Blot-analysis. Cell extracts of untreated cellsor of cells that were treated with si-LamA1-VLP or siGL2-VLP wereharvested 44 hours after the treatment, and stained with an anti-laminA/C-antibody. The lamin A/C-content was identical in both control lanes,wherein the portion of lamin A/C in siRNA-VLP-treated populations wasmarkedly reduced. In order to confirm a uniform protein loading, theblots were analyzed in parallel with regard to vimentin.

C) In addition to the siRNA-molecules, a linearized expression constructencoding for eGFP was packaged into VLP and transduced into gliomacells. 24 hours after this treatment nearly all cells showed a positiveGFP-expression.

FIG. 2: Qualitative and quantitative documentation of the successfulintroduction of siRNA by means of modified VLF.

A) The diagram shows the data of a quantitative Western Blot-analysis ofthree individually performed experiments, wherein siRNA was introducedinto HeLa SS6-cells and MCF7-cells using PEI-Tf-VLPs. The treatment ofcells with PEI-Tf and siRNA, siRNA alone, empty PEI-Tf-VLPs, andPEI-Tf-VLPs which were loaded with non-related siRNA-molecules, servedas individual negative controls. Only the treatment of PEI-Tf and siLamAcaused a weak (15-20%) reduction of the content of the target protein,whereas siRNA which was packed into VLPs at an amount of 50 nM alreadywas more efficient. The loading of the VLPs with 5 μM siRNA, and thesubsequent complexation with PEI-Tf led to a nearly completedown-regulation of lamin A/C. Other siRNA-molecules that are directedagainst lamin A/C, one of which was conjugated with and withoutfluorescein at the 5′-end of the sense strand, showed a comparableeffectivity regarding the down-regulation in HeLa-cells. A second set ofsiRNA-molecules which were directed against human emerin, was examinedon MCF-7-cells. As shown by quantitative Western Blot-analysis, in allthree cases the siRNA was successfully introduced into the cells. Thebottom field shows representative blots after ECL-development. In allcases, vimentin was used as a loading control.

B) A fluorescence microscopy image of HeLa-cells that were treated withsiLamA-F-PEI-Tf-VLPs shows the uptake of siRNA-molecules (green) and thedosage-dependent down-regulation of lamin A/C (red). Compared to thehigher loading concentrations (bottom field), the effects on thedown-regulation of a target gene are weaker, when siRNA is incorporatedinto VLPs at a concentration of 50 nM (field in the middle). In thecontrol cells, a reduction of the lamin A/C-content can not be observed,when they were treated with VLPs containing non-related siRNA-molecules(top field).

FIG. 3: Transient RNA-interference in human T-cells.

Human Supt1-cells were stimulated with desferrioxamine 24 hours beforethe treatment with siRNA-loaded PEI-Tf-VLP.

A) A confocal fluorescence microscopy of a single supT1-cell 24 hoursafter the treatment with VLPs shows a homogenous dispersion offluorescent siRNA-molecules (siLamA-F) in the cytoplasm. Sections alongthe Z-axis show that the presence of the siRNA is mainly limited to thecytoplasm, and nearly no fluorescence signal can be observed at theperiphery or in the nucleus of the cell.

B) After introduction into the cell, anti-emerin-siRNA-siEme1 clearlyshowed that this siRNA is available for the RNA-interference machineryof the cell. An indirect immunfluorescence microscopy usinganti-emerin-antibodies showed a strong down-regulation of emerin in thesiEme-PEI-Tf-VLP-treated population, whereas the emerin content in thecontrol population, which was treated with siGL2-PEI-Tf-VLP, remainedunchanged.

C) The results of the immunofluorescence microscopy were confirmed usingWestern Blot-analysis. Only the siEmei-PEI-Tf-VLP-treated populationshowed a down-regulation of emerin, whereas the control cells, whichwere treated with siGL2-PEI-Tf-VLP or empty PEI-Tf-VLP, and the cells,which were only treated with siEmei and PEI-Tf, did not show a reductionof the emerin content. The loading of equal amounts of protein wasconfirmed by staining of the membrane with Ponceau red (dye is shown inthe background).

FIG. 4:

Sequence modifications of the VP1-protein.

A) Comparison of amino terminal sequences of the polyoma JC-virus wildtype VP1 and the chimeric VP1-protein (VP-Mut2), which contains atwo-part nuclear localization signal due to an amino acid insertion. Thesequences as derived from the viruses SV40 and BKV, which formed thebases for the modifications, are shown for comparison.

B) In electron microscopy imaging, the chimeric VP1-protein Mut2 showedthe same de- and reassembly characteristics as the wild typeVP1-protein.

C) The chimeric VP1-protein Mut2 showed a higher transduction efficiencyin SVG-glial cells than the wild type-protein. Following thetransduction of a luciferase-expression construct, the relativeluciferase-activity was determined.

FIG. 5:

By coupling of ligands to lysine residues of VP1, a retargeting becomespossible. One example for a heterobifunctional linker molecule beingable to couple amino to sulfhydryl groups, is shown above. Using thislinker molecule (or analogous linker molecules), lysine residues on afirst protein (e.g. VP1) and cysteine residues on a second protein (e.g.ligand) can be interconnected. In the middle part of the Figure, thestructure of the JCV-VP1 proteins as calculated, and, schematically, thelinker molecule when coupled to an accessible lysine residue are shown.At the very bottom, the JCV-VP1-protein is shown in a top view (i.e.from the outside of the capsid). Both lysine residues K60 and K164 thatare suitable for a coupling of ligands are indicated. These lysineresidues can be used for attaching a heterobifunctional linker moleculeas shown above.

1. A composition, comprising a virus-like particle (VLP) wherein saidVLP comprises at least one viral capsid protein, and wherein at leastone RNA-interference (RNAi-) inducing molecule is included in theinterior of the VLP.
 2. The composition according to claim 1, whereinsaid RNAi-inducing molecule is an RNA and/or an RNA-analog.
 3. Thecomposition according to claim 2, wherein said RNA is siRNA, miRNA,dsRNA, shRNA or a precursor thereof.
 4. The composition according toclaim 1, wherein said RNAi-inducing molecule is a DNA and/or aDNA-analog, encoding siRNA, miRNA, dsRNA, shRNA or a precursor thereof.5. The composition according to claim 4, wherein the DNA comprisesregulatory elements expression in a target cell.
 6. (canceled)
 7. Thecomposition according to claim 1, wherein the ratio of the masses of VLPto RNAi-inducing molecule is from 1:1 to 20:1.
 8. The compositionaccording to claim 1, wherein said VLP comprises the capsid protein VP1of the human polyoma JC virus.
 9. The composition according to claim 1,wherein said VLP is free from other components of an authentic virus.10. The composition according to claim 1, wherein at least one capsidprotein of the VLP is modified.
 11. (canceled)
 12. The compositionaccording to claim 1, wherein at least one capsid protein of the VLP isassociated with at least one target cell-specific group.
 13. Thecomposition according to claim 12, wherein said target cell-specificgroup is a ligand that is able to bind to one or more receptors that arepresented on the cellular surface of the target cell.
 14. Thecomposition according to claim 13, wherein said ligand is a transferrinand said receptor is a transferrin receptor.
 15. The compositionaccording to claim 12, wherein said target cell-specific group isassociated with at least one capsid protein of the VLP by means of oneor more chemical linker groups.
 16. The composition according to claim15, wherein said linker group is a cationic polymer.
 17. The compositionaccording to claim 16, wherein said cationic polymer is polyethyleneimine.
 18. The composition according to claim 10, wherein said capsidprotein is a fusion protein with a fusion part.
 19. The compositionaccording to claim 18, wherein the fusion part of the fusion proteindoes not interfere with the formation of the VLP.
 20. The compositionaccording to claim 18, wherein the fusion part of the fusion protein isable to bind to receptors that are presented on the cellular surface ofa target cell.
 21. The composition according to claim 1, wherein the VLPcomprises a modified capsid protein that has a host spectrum that is notidentical to a host spectrum of the unmodified VLP.
 22. The compositionaccording to claim 1, wherein said capsid protein of the VLP isrecombinantly produced.
 23. A method for introducing RNAi-inducingmolecules into a target cell wherein said method comprises contacting atarget cell with a composition of claim
 1. 24. (canceled)
 25. The methodaccording to claim 23, wherein the cell is a mammalian cell.
 26. Themethod according to claim 25, wherein the mammalian cell is of humanorigin.
 27. The method according to claim 23, wherein the expression ofat least one gene in the target cell correlates with a pathologic state.28. (canceled)
 29. The method according to claim 23, wherein theexpression of at least one endogenous gene is increased in the targetcell.
 30. The method according to claim 29, wherein the increasedexpression of the endogenous gene correlates with a pathologic state.31. (canceled)
 32. A method for producing a medicament for thediagnosis, prevention and/or treatment of a disease or a disease statecaused by the expression of a nucleic acid that stems or is derived froma pathogenic organism, or by the increased or undesired expression of anendogenous gene wherein said method corn rises the use of a compositionof claim
 1. 33. A method for producing a composition according to claim1, comprising the assembly of the viral capsid proteins into a VLP inthe presence of the RNAi-inducing molecules.
 34. The method according toclaim 33, comprising coupling of a target cell-specific group to the VLPthat is able to bind to one or more receptors on the cellular surface ofa target cell.
 35. A method for introducing RNAi-inducing molecules intoa target cell, comprising the steps: (i) assembly of the viral capsidproteins into a VLP in the presence of the RNAi-inducing molecules, and(i) contacting the VLP loaded with the RNAi-inducing molecules with thetarget cell under conditions that allow for an uptake of theRNAi-inducing molecules into the target cell.
 36. The method accordingto claim 35, comprising coupling of a target cell specific group to theVLP that is able to bind to one or more receptors on the cellularsurface of a target cell.
 37. A method for down-regulating at least onegene in a target cell, comprising the steps: (i) providing a compositionaccording to claim 1, and (ii) contacting of the composition from step(i) with the target cell under conditions that allow for an uptake theRNAi-inducing molecules into the target cell.
 38. A test kit forintroducing RNAi-inducing molecules into a target cell, comprising acomposition according to claim
 1. 39. A pharmaceutical compositioncomprising VLP and RNAi-inducing molecules according to claim 1,optionally together with one or more buffers, auxiliary agents andadditives and/or diluents.
 40. A method for the therapy and/or diagnosisof a disease or a disease state caused by the expression of a nucleicacid that stems or is derived from a pathogenic organism, or by theincreased or undesired expression of an endogenous gene, wherein saidmethod comprises administering, to a subject in need of such therapyand/or diagnosis, a composition of claim
 39. 41. A modified JCV-VP1capsid protein comprising a heterologous nuclear localization signal, ora nucleic acid encoding therefor; or a VLP-composition containing saidmodified JCV-VPI capsid protein.
 42. A VLP-composition, wherein at leastone immune stimulatory nucleic acid, optionally in combination withpolypeptide or peptide immunogen, an aptamer or an siDNA-molecule, isincluded in the interior of the VLP.
 43. A JCV-VP1 capsid protein towhich at least one heterologous binding partner is bound via the aminoacid residues K60 and/or K164.